The speed regulator formed by a device of said type is also referred to as cruise control. The speed regulation may also be enhanced to include distance regulation, in which case the speed is also adapted to that of a vehicle travelling ahead, this commonly being referred to as adaptive cruise control. A method of said type and a device of said type are known in each case from EP 2 162 337 B1 and from US 2005/0167175 A1.
Normally, upon actuation of the brake pedal while a cruise control is engaged, the cruise control is interrupted but not switched completely off, so that the speed regulation function can be reactivated/re-engaged by actuation by the driver of a control such as the accelerator pedal or a switch or button. If the cruise control function is interrupted in this way, the vehicle does not maintain the present speed upon the release of the brake pedal or switch/button, but is decelerated by the engine or motor drag torque, as disclosed in EP 2 162 337 B1 (also published as US2010/056337A1). This reaction may generally be considered desirable owing to the associated feedback to the driver.
Such a reaction also occurs when the cruise control is fully switched off, and is expected by the driver. However, until now, consideration has not been given to the fact that the driver can perceive the switching-off reaction to be disturbing if it results in a vehicle deceleration that is greater (more abrupt) than normal, and other vehicle occupants often perceive this disturbance to an even greater degree. This may arise in particular if the vehicle is loaded in an aerodynamically unfavorable manner. For example, if bicycles or other cargo are loaded on the roof of the vehicle, or if the folding top of a convertible is open, because in those cases air resistance imparts a greater braking action than is otherwise normal for the same vehicle when it is aerodynamically “clean.” The sudden vehicle deceleration upon the cruise control being fully switched off may also be more abrupt than normal if the vehicle is travelling on an uphill grade, and conversely, undesirably high acceleration can occur if the vehicle is presently travelling on a downhill grade. Experienced drivers may anticipate such reactions and lightly press the accelerator pedal or the brake pedal before switching off the cruise control.
US 2005/0167175 A1, teaches that the target speed of a cruise control system may be varied in steps (for example, steps of 10 km/h) and that during a change in the target speed the associated deceleration or acceleration is limited to a maximum value so as not to disturb the vehicle occupants. However, said limitation is implemented only for as long as the cruise control is active. If the cruise control is completely switched off, even when it is presently in an interrupted state, undesirable and/or uncomfortable vehicle acceleration or deceleration can occur in the situations described above.